240 O. C. Marsh—New Tertiary Mammals. 
the close correspondence of the skeleton with that of the Le- 
murs, and by the general structure of the skull. Hyopsodus and 
the present genus represent a distinct family, which may be 
called Lemuravide. The type genus, Lemuravus, has 44 teeth, 
indicating the most generalized form of the order. Hyopsodus 
as apparently but 42. In the former, the teeth form a contin- 
uous series above and below. The canines are small, and the up- 
sg incisors are not separated on the median line, asin Lemurs. 
he molar teeth appear to be essentially the same as those of 
Hyopsodus, but as the latter are only known with certainty 
from the lower jaw first described there may be important dif- 
ferences. The symphysis of the lower jaw is completely cods- 
sified. The brain was nearly smooth, and of moderate size. 
The skeleton most resembles that of the Lemurs. The humerus 
has at its distal end a supracondylar foramen, and a supra 
trochlear perforation. e radius and ulna are distinct. The 
femur has a small pit in the head for the round ligament. Its 
distal end is more flattened antero-posteriorly than in the 
Lemurs. The tibia and fibula are separate. The astragalus 1s 
very similar to that of Lemur. 
Measurements. 
Space occupied by entire upper dental series, ---- ----- SO 
eebuy Ge WODGE NIOIST SOTIOI Sn in od = 21°5 
Extent of three upper true molars,...........-.------ 11° 
Extent of three upper incisors, .....-..........-.---- 5°5 
Extent of lower molar s pee pee orca 23° 
Extent of three lower true molars,__...._._...------- 12°5 
Suameter Gf Rekd of femitr, 2: oc i es te 5° 
Transverse diameter of distal end of femur,._..-.----- 10 
Transverse diameter of proximal end of tibia, -. ..----- 9° 
Transverse diameter of distal end, sss ont ee 
laength of astrapalus,..o.oo- 2 nsec ic skpcs Gee 75 
The present species was about the size of the largest squirrels. 
The type specimen was found in 1871, in the Lower Hocene of 
Wyoming, by Mr. T. G. Peck of the Yale party. 
Laopithecus robustus, gen. et sp. nov. 
Secs ee tet eee 
